An atmospheric cluster database consisting of sulfuric acid, bases, organics, and water

Abstract

We have collected, recomputed, and compiled a database consisting of 633 unique atmospherically relevant molecular clusters containing sulfuric acid, bases, oxidized organic compounds, and water. The database is composed of strongly hydrogen-bonded molecular clusters and spans neutral, negatively charged, and positively charged clusters of atmospheric relevance. All the cluster structures and vibrational frequencies have been re-evaluated at the ωB97X-D/6-31++G(d,p) level of theory, and the single point energies have been refined using a high-level DLPNO-CCSD(T)/aug-cc-pVTZ calculation. The database unifies published atmospheric molecular clusters under a single common methodology and serves as an efficient look-up table for molecular cluster structures and thermochemical parameters. Utilizing the database, the performance of four semi-empirical methodologies (PM6, PM7, B97-3c, and PBEh-3c) in calculating the binding energies of atmospheric molecular clusters is assessed. It is identified that the B97-3c and PBEh-3c empirically corrected density functional theory methods yield low errors in the binding energies compared to DLPNO-CCSD(T)/aug-cc-pVTZ reference results and that a simple linear model can be utilized for estimating accurate binding energies based on ωB97X-D/6-31++G(d,p) results.